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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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S56                                 ALASKAN GLACIER STUDIES
southern end of Willard Island.   The correct position of the terminus of the glacier was first mapped in 1909 by Grant and Higgins.
A "comparison of their photographs with ours taken in 1910 shows a slight advance of the glacier during that year. It is not certain exactly how much advance there was, but a rock ledge exposed in 1909 beneath the eastern side of the terminus was overridden in 1910 and the tidal frontage was slightly increased. The western edge, toward Northland Glacier, covered more of the bare rock slopes near sea level in August, 1910, than in July, 1909. At several points along this western portion of the terminus, ice blocks were sliding down from the end of the glacier into the sea as a result of this advance.
Beloit and Marquette Glaciers. These are two adjacent cascading glaciers, Beloit Glacier being at the very head of Blackstone Bay, while Marquette Glacier lies a short distance northeast of it. The latter has a much gentler slope than the former. Beloit Glacier descends from a gently sloping upper portion, at about the same level as Black-stone Glacier, and terminates at sea level in a vertical ice cliff from which bergs were discharged in 1909 and 1910, there being no appreciable change in the ice front during the period of observation. Both of the glaciers are without medial or lateral moraines, < Beloit Glacier being severely crevassed, while Marquette Glacier is rather smooth. The former is fed from neve" fields adjoining the Blackstone Glacier and is separated from the Marquette Glacier by a mountain ridge, the upper portion of which is covered with neve which feeds into each of the glaciers. In 1909 and 1910 Marquette Glacier terminated a few hundred feet from the water's edge and underwent no appreciable change during that period. It was covered with snow nearly to sea level in August, 1910.
Ripon and Lawrence Glaciers. These two cascading glaciers are on the eastern side of Blackstone Bay, Lawrence Glacier being about three quarters of a mile northeast of Marquette Glacier, and Ripon about the same distance farther to the northeast. On Applegate's map both of these glaciers seem to reach tidewater, but the author of the map did not go near enough to them for us to feel certain that this is correct. In 1909 and 1910, each of the glaciers terminated 150 to 200 feet from the fiord.
Each of the glaciers is moderately crevassed and without moraines. They are both deeply set in mountain valleys, separated by broad rock spurs and are fed from extensive neVe fields which mantle the whole mountain slope. Their surface slope is 18 to 20, or about the same as Marquette Glacier, and not nearly so steep as the slope of the Beloit and Blackstone Glaciers. The n6v6 fields on the slopes of Mt. Applegate, east of Ripon Glacier, mantle large areas and feed an unnamed glacier lobe in the next valley to the northeast, as well as a number of other small lobes.
In 1910 portions of the terminus of Lawrence Glacier were so near the water's edge that ice fragments were sliding down the bare rock slope into the bay, so that this glacier was discharging small icebergs without being a tidal glacier. A small, but clear-cut, stony, push moraine, forming the boundary of a moderate-sized barren zone between the moraine and the ice, extended around parts of the terminus of Lawrence Glacier, excepting in the middle where the ice fragments were discharged. Within this barren zone there were only scattered young shrubs, while dense, mature forest grew outside.
The terminus of Ripon Glacier lies farther back from the sea than that of Lawrence Glacier, ending on bare rock ledges. The nose of the glacier was mantled in places